It is customary in many municipalities to bury water and gas valves beneath the surface of the earth or roadway. Access to such a valve is provided through a pipe extending upwardly from the the valve to the surface. An access cap is employed to close the upper end of the pipe.
The access cap may rest loosely on the upper end of the pipe. But such caps are easily dislodged, leaving the pipe exposed to debris. For such installations, debris caps have been devised to be placed in the access pipe to keep the pipe from filing with debris.
Debris caps for this purpose are disclosed in the following U.S. Patents: U.S. Pat. No. 4,921,123, granted May 1, 1990, to G. J Mizock, and U.S. Pat. No. 5,439,130, granted Aug. 8, 1995, to G. C. Waugh.
The separate debris cap could be eliminated were the access cap designed in such a manner to be reliably retained in place on the access pipe.
U.S. Pat. No. 4,048,766, granted Sep. 20, 1977, to P. H. Dantzer et al. for "Closure Lid Assembly for Protective Housings" discloses a lid assembly in terms of a locking mechanism for the lid but discloses no details of construction.